A
line-replaceable unit (LRU),
lower line-replaceable unit(LLRU),
line-replaceable component (LRC), or
line-replaceable item (LRI) is a modular component of an
airplane,
ship or
spacecraft (or any other manufactured device) that is designed to be replaced quickly at an operating location. An LRU is usually a sealed unit such as a
radio or other auxiliary equipment. LRUs are typically assigned logistics control numbers (LCNs) or work unit codes (WUCs) to manage
logistics operations.